Lapping tool



Patented Feb. I, 1944 LAPPING- TOOL Arch W. Harris, Cleveland, Ohio, assignor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey N Drawing. Application August 15, 1942, Serial No. 454,996

2 Claims. (Cl. 51-309) This invention relates to lapping tools and the like, n

More particularly, my invention contemplates a lapping tool adapted for what is termed an intermediate lap, employed between roughing and "finishing lapping operations to produce a uniform surface without final smoothness and polish.

As in the finishing of hard steel metal-working rolls, the intermediate loop may be employed as one of a sequence of lapping operations toward an ultimate fine finish and polish, or may be employed for leveling and finishing without further finishing and polishing operations where desired.

I have provided a lap capable of use wet, whereby the abrasive grain may 'be fed to the tool with water as a vehicle, while at the same time effecting a desirable dissolution of the surface of the tool to prevent loading and accumulation of the grain and cuttings.

For such purpose, I employ a lapping tool molded from an alloy of lead and one of the group consisting of metallic sodium, potassium or calcium. The addition of one of the metals of said group to lead produces a deliquescent composition which readily absorbs moisture. Hence,

by supplying wet abrasive to the face of a tool formed of such material, the composition undergoes partial dissolution, thereby maintaining the face of the tool clean and free of abrasive loading.

group of metals may be successfully employed with lead as the remainder of my lapping com- From about 1% to 4% by weight of one of said position and tool thereof without the hazard of too rapid disintegration in air. The disintegration of the alloy of the stated proportions is slow and may be arrested by coating with oil or grease. Also, the tool so composed may be stored in a sealed container without substantial injury thereto when not in use. As a specific example within the foregoing proportions, I have found that a lead-sodium composition containing about 2% sodium by weight is suitable for an intermediate lap for the pur poses stated in lapping hard steel surfaces, the said composition being suiilciently deliquescent while at the same time remaining stable and cohering in a block or tool during use. A

The deliquescent alloy so provided has the marked advantage of acting as a rust inhibitor when used with water upon steel or the like, since .I

the dissolution product of the action is alkaline in character.

Various changes and modifications are contemplated within the scope of the following claims.

I claim:

1. An intermediate lap consisting of lead containing from about 1% to 4% by weight of one of the group consisting of metallic sodium, potassium and calcium, molded into block form, characterized by possessing deliquescence when employed in the presence of water.

2. An intermediate lap consisting of lead containing about 2% sodium by weight, molded into black form, characterized by possessing deliquescence when employed in the presence of water.

ARCH W.HARRIS. 

